1. Field of the Invention
The invention generally relates to a single-ended static random access memory (single-ended SRAM), and more particularly, to a single-ended SRAM able to cross-point data-aware write data operated at a sub-threshold low-voltage.
2. Description of Related Art
The science and technology about computer today are developing faster and faster, in which the memory technology closely related to the computer science and technology plays a vital key role. According to whether or not the data is kept or deleted after the power is off, the memory is divided into non-volatile memory and volatile memory. For the non-volatile memory, the data can be kept after the power is off, while for the volatile memory, the saved data is deleted after the power is off. Further, the volatile memory is divided into dynamic random access memory (DRAM) and static random access memory (SRAM).
FIG. 1 is a schematic circuit diagram of a conventional SRAM, in which a SRAM 100 includes six transistors M1, M2, M3, M4, M5 and M6. The transistors M1, M2, M3 and M4 are coupled between a reference power Vcc and a reference ground GND and form two inverters connected in series to each other. The gates of the transistors M6 and M5 respectively receive a word-line signal WWL and a word-line signals WRL, while the sources (or drains) of the transistors M5 and M6 respectively coupled to a bit-line BWL and a bit-line BRL.
The SRAM 100 is a single-ended writing/reading SRAM, in which the data to be written can be written into a data-latching unit formed by the transistors M1-M4 via the transistor M5 through the bit-line BWL. The transistor M6 and the bit-line BRL provide the SRAM 100 with a data-reading path.
In the SRAM 100, in order to smoothly conduct the above-mentioned single-ended writing operation, the channel aspect ratio (ratio of channel width over channel length) of the transistor M5 should be sufficient for providing enough current driving capacity. However, such requirement unavoidably increases the circuit area of the SRAM 100 and leads to higher fabrication cost.